1. Field of the Invention
This invention relates to a method of fabricating a semiconductor device or semiconductor integrated circuit device, and more particularly to a method for providing isolation between elements of such a device using an oxide.
2. Description of the Prior Art
An isoplanar technique is disclosed in, for example, U.S. Ser. No. 111,956 filed on Feb. 2, 1971 by Fairchild Camera and Instrument Corporation. Such isoplanar technique is known as an effective method for providing isolation between elements of a semiconductor device or semiconductor integrated circuit device, and an oxide of electrical insulator is used for the isolation. This method is advantageous over a known method for element isolation utilizing a PN junction in that the parasitic capacitance can be reduced, the mask alignment can be achieved with reduced error, etc.
However, due to the fact that this method utilizes an oxide layer formed by thermal oxidation of an electrical insulator on a semiconductor substrate of the isolation between elements of a semiconductor device or semiconductor integrated circuit device, a projecting area or a so-called bird beak or bird head tends to appear the oxide layer giving rise to such a trouble that a conductor layer deposited subsequently on this oxide layer tends to be disconnected in the vicinity of the bird beak or bird head. Futher, this method has such a disadvantage that crystal distortion adversely affecting the elctrical properties of the divice tends to occur due to the fact that the semiconductor substrates exposed to a high temperature over a long period of time during the formation of the oxide.